Father in custody after house fire that killed three children as premier says 'deep wound' left

NSW Premier Chris Minns has called a house fire in Sydney's west that killed three young children a "horrifying and senseless act", as police allege their attempts to rescue those inside were thwarted by the children's father trying to block access.

Emergency services were called to a home in Lalor Park in the early hours of Sunday after a house fire that claimed the lives of three children. Source: AAP / Thomas Parrish

This story contains references to alleged domestic violence.

NSW Premier Chris Minns said a 28-year-old man will be hit with "the most serious charges on offer" after three children were killed in a house fire in Sydney's west on Sunday night.

The father of the children — aged six, two and five months — allegedly tried to prevent them from being rescued as flames raged around them.

Neighbours and emergency services rushed to the scene at 1am on Sunday, as the Lalor Park house was engulfed by fire.

But police allege their attempts to rescue those inside were thwarted by the children's father trying to block access to the home.

Police are investigating the Lalor Park house fire as an alleged domestic-related multiple homicide. Source: AAP / Mark Evans

Two boys, aged three and six, were rescued from the burning home and taken to Westmead Hospital in a critical condition but died a short time later.

The body of the third child, believed to be a 10-month-old girl, was found after firefighters extinguished the blaze.

Four other children — three boys aged four, seven and 11, and a 9-year-old girl — are all being treated in hospital following the incident but are expected to survive.

Police allege suspect tried to thwart first responders

The NSW premier said the "horrifying and senseless act" had outraged the entire state.

"These children deserved a loving home with safety and security and, instead, they're gone," Minns said on Monday.

"I can imagine the people of NSW feel enormous sorrow and deep sympathy with the surviving family members this morning, as we also show enormous care and gratitude to our emergency service workers ... this is going to leave a deep wound on the state of NSW."

The incident is being treated by police as a domestic-related multiple homicide.

Homicide squad detective superintendent Danny Doherty said that "at this stage, it does appear that the 28-year-old man is responsible for multiple deaths of young lives".

Homicide squad detective superintendent Danny Doherty said police will allege the man "did certain actions to prevent the rescue of those young lives". Source: AAP / Mark Evans

"There were direct actions taken ... that were intentional of keeping police, other first responders and neighbours out of the property while it was on fire," he told reporters.

"We're alleging that this man did certain actions to prevent the rescue of those young lives."

"(Police) will allege that this 28-year-old man's actions were linked directly to the cause of the death of these three young people," he said.

The man is in a coma in an intensive care unit, being treated for smoke inhalation and burns.

Acting superintendent Jason Pietruszka said attempts to enter the burning home were allegedly met with resistance as police officers and a neighbour heroically tried to rescue children from the fire.

Acting police superintendent Jason Pietruszka said neighbours and police officers tried to enter the burning building and suffered minor injuries as a result. Source: AAP / Mark Evans

Those efforts were the reasons four children and their mother were able to escape, he said.

"It's completely and utterly devastating for people who know the family, that go to school with the other children — it's a close-knit community and this will have a long-lasting impact," he said.

Their 29-year-old mother was also taken to hospital suffering smoke inhalation and is also sedated.

"It's completely and utterly devastating," Pietruszka said.

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